Abu Jafar (as) said: O Abdullah! There is none from an Eid of the muslims, be it Adha or Fitr, except that it renews grief (yujaddidu huznan) of the Progeny (as) of Muhammad (s). I said: And why is that so? He (as) said: Because they (the Progeny) are seeing their (as) rights in the hands of others (haqqahum fi yad-e-ghayr).
[Al Kafi Vol 4 The Book of Fasts Ch 74 H2]
Imam Baqir (as) said: On every Eid, either Eid-ul-Fitr or Eid-ul-Adha, it brings grief to Aal-e-Muhammad (the Progeny of Muhammad). I (the narrator) asked: Why is that? The Imam (as) said: Because they (the Progeny) see their rights have been taken away by the others (their enemies).
[Man la yahdharul faqih, V1, P507, #1480]
Should we rejoice on the day of Eid and celebrate it in a festive mood? Or should we observe the aamaal in a melancholy mood?